Western Ringtail Possum Pseudocheirus occidentalis Conservation Status: Critically Endangered

Identification

The western ringtail possum Pseudocheirus occidentalis is a small arboreal marsupial found in the south-west of Western Australia, characterised by a slender prehensile tail with a white tip which is as long as or longer than the rest of its body. The tail fur is very short. The fur is a dark chocolate brown to dark grey above and creamy white or grey below.

The species is distinguished from the common brushtail possum Trichosurus vulpecula by its smaller size, shorter and usually darker fur, smaller rounder ears and absence of a brushtail. No other large possums occur in the south-west of WA.

Head and body length: 30-40 cm Tail length: 30-41 cm Weight: 700-1300g (males) 750-1200g (females)

Taxonomy

Family: Pseudocheiridae Genus: Pseudocheirus Species: occidentalis Other common names: Ngwayir, Womp, Woder, Ngoor, Ngoolangit

Distribution and Habitat

Western ringtail possums were historically widely distributed throughout the southwestern forests of WA, extending to southeast of Geraldton and to the southern edge of the Nullarbor Plain. Their current distribution is patchy and largely restriced to near coastal areas of Peppermint woodland and Peppermint/Tuart associations from the Australind/Eaton area to east of Albany at Waychinicup National Park, and in the southern forest near Manjimup.

There are three main areas known to, or previously known to, support large numbers of western ringtail possums. These three management areas are:

Swan Coastal Plain zone: Peppermint woodlands and Peppermint/Tuart forests on the southern extremity of the Swan Coastal Plain, principally around Busselton.

Southern Forest zone: Jarrah forests near Manjimup where Peppermint is generally absent.

South Coast zone: a diverse range of vegetation types between Denmark and Mount Manypeaks, but principally in near-coastal limestone heath, Jarrah Marri thicket woodland and forest, riparian, Peppermint woodland and Karri forest vegetation.

For further information regarding the species distribution, please refer to www.naturemap.dpaw.wa.gov.au.

Photo: A. Wayne/DBCA

Current distribution of western ringtail possums (DBCA, 2017)

FAUNA PROFILE – Western Ringtail Possum Pseudocheirus occidentalis

Community Involvement

If you think you have seen a western ringtail possum, fill out a fauna report form and send it to the Department’s Species and Communities Branch at fauna@dbca.wa.gov.au. The Department keeps track of the distributions of threatened species to help monitor population trends and inform management decisions.

If you find a sick, injured or orphaned western ringtail possum, contact the Wildcare 24-hour Helpline on (08) 9474 9055.

The Department runs a variety of volunteer projects across WA including scientific research, community education and manual labour. Further information about these opportunities can be found on the Department’s webpage.

Biology and Behaviour

The western ringtail possum is a highly arboreal nocturnal species that spends the majority of its time feeding, resting and socialising in tree canopies. Western ringtail possums build nests or dreys in low shrub thickets, sedges, rushes, grass trees and within various tree canopies. Other diurnal resting sites include tree and log hollows. In suburban areas, western ringtail possums may also rest in roof spaces and other dark cavities in houses.

Western ringtail possums have a relatively small home range at less than 5ha. They will use 2-7 rest sites within their home range but may use up to 20 throughout the year. Adult western ringtail possums normally rest alone during the day and interacting socially at night. They are leaf-eating herbivores and their diet is almost exclusively comprised of Peppermint Agonis flexuosa, Marri Corymbia calophylla and Jarrah Eucalyptus marginata. In urban areas, they are also known to feed on introduced garden species including rose flowers and the leaves and fruits of fruit trees.

Females generally give birth in late autumn and winter, but some coastal populations breed throughout the year. Litter size is usually one young, but there are rare occurrences of 2-3 young in a litter. The gestation period ranges between 2-4 weeks, with young emerging permanently from the pouch at approximately 3 months. Young are fully weaned at 6-8 months, dispersing from their mother’s home range from 8-12 months.

Conservation Status

The western ringtail possum is recognised as a threatened species under State and Commonwealth legislation. In Western Australia the species is listed as fauna that is ‘likely to become extinct’ in the wild (Specially Protected) under the Wildlife Conservation Act 1950 and has been assigned the threat status ranking of Critically Endangered using International Union for Conservation of Nature (IUCN) criteria. Nationally the species is listed as Critically Endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.

The species has experienced declines in abundance and habitat across its range since colonial settlement. The threatening processes are complex, interactive and often population specific. Habitat loss and fragmentation from urban development and mining are considered the most immediate threats to coastal and near-costal populations, while introduced predators, climate change, timber harvesting and fire are the major threats for the Jarrah forest populations. Other threats impacting on the species include:

Competition for tree hollows with brushtail possums, the feral European honey bee and parrots;

Reduction in habitat quality and food supply due to pathogens, insects and climate change;

Risk of injury, death and disease in urban areas due to human activities; and

Unregulated relocation of orphaned, injured and rehabilitated western ringtail possums to unsuitable areas.

Management

Recovery Plan

A national recovery plan has been produced for the western ringtail possum, and outlines the recovery actions required to prevent further decline in distribution and abundance of the species. Management objectives from this plan include:

Protect and manage habitat critical for survival to maintain viable populations of western ringtail possums;

Mitigate threatening processes constraining the recovery of western ringtail possums;

Achieve an evidence-based management approach for western ringtail possums;

Manage displaced, orphaned, injured and rehabilitated western ringtail possums for the best conservation

FAUNA PROFILE – Western Ringtail Possum Pseudocheirus occidentalis

outcome for the species, and;

Raise awareness of the status of western ringtail possums and gain support and behaviour change to mitigate threatening processes.

Existing Conservation Measures

The Western Ringtail Possum Recovery Team, led by the Department of Biodiversity, Conservation and Attractions, reformed in 2017 to assist with the implementation of recovery actions as outlined in the current recovery plan.

The Department of the Environment and Energy has published a policy statement that provide guidelines for determining whether a proposed action on the southern Swan Coastal Plain is likely to have a significant impact on the western ringtail possum and its habitat.

There are conservation requirements through statutory and local government planning approvals, including conditions placed on developments, to deal with development-related impacts on the western ringtail possum.

The Department’s Western Shield animal conservation program controls the impacts of foxes and feral cats.

There are various research, education, local government and community projects that contribute to the conservation of the western ringtail possum and its habitat.

Citation

Department of Biodiversity, Conservation and Attractions. (2017). Fauna Profile - Western Ringtail Possum Pseudocheirus occidentalis. Retrieved from http://www.dbca.wa.gov.au/

Key References and Further Reading

Department of the Environment and Energy (2016). SPRAT Profile: Pseudocheirus occidentalis – Western ringtail possum, Ngwayir, Womp, Woder, Ngoor, Ngoolangit. Retrieved from: http://www.environment.gov.au/sprat

Department of the Environment, Water, Heritage and the Arts (2009). Significant impact guidelines for the vulnerable western ringtail possum (Pseudocheirus occidentalis) in the southern Swan Coastal Plain, Western Australia – EPBC Act policy statement 3.10. Retrieved from: http://www.environment.gov.au/resource/significant-impact-guidelines-vulnerable-western-ringtail-possum-pseudocheirus-occidentalis

Department of Parks and Wildlife (2017). Western Ringtail Possum (Pseudocheirus occidentalis) Recovery Plan – Western Australian Wildlife Management Program No. 58. Perth, WA: Department of Parks and Wildlife. Retrieved from: http://www.environment.gov.au/cgi-bin/sprat/public/publicshowallrps.pl

Shedley, E. & Williams, K. (2014). An assessment of habitat for western ringtail possum (Pseudocheirus occidentalis) on the southern Swan Coastal Plain (Binningup to Dunsborough). Bunbury, WA: Department of Parks and Wildlife.

Van Dyck, S. & Strahan, R. (Eds.). (2008). The Mammals of Australia (3rd ed.). Sydney, NSW: Reed New Holland.

Woinarski, J., Burbidge, A. & Harrison, P. (Eds). (2014). The Action Plan for Australian Mammals 2012. Collingwood, VIC: CSIRO Publishing.

Disclaimer

The State of Western Australia and its employees do not guarantee that this publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence that may arise from you relying on any information in this publication.